New Insights Into the Heterogeneity of the Lithosphere-Asthenosphere System Beneath South China From Teleseismic Body-Wave Attenuation

Teleseismic body-wave attenuation provides an independent constraint on the architecture of the lithosphere-asthenosphere system. We obtain the first map of teleseismic attenuation across South China, which correlates well with previous estimates of lithospheric thickness. The weakest attenuation occurs in the Sichuan Basin, where continental lithosphere is thick, and in the adjacent Chuandian region, which we attribute to delaminated lithosphere, or lithosphere strengthened by an ancient plume based on comparison with previous studies. Smaller batches of remnant or delaminated lithosphere may cause local minima along the eastern coast. Pronounced negative anomalies occur in the Hengyang, Jianghan and Nanchang basins, motivating the hypothesis that the basins occur where locally strong blocks within the lithosphere resisted the pervasive deformation of South China. The strongest attenuation occurs in a broad region in the vicinity of the Hainan plume, which is consistent with high temperatures and possibly partial melt in the upper mantle.